This is all no easy feat, and is specifically enabled by the writing’s tightly woven relationship to a variety of interconnected gameplay features, such as chess-like hero battles; currencies like ‘Renown’, supplies, and your caravan’s supply of people; and more abstract systems like time limits and your party’s level of morale. Take a look at the diagram opposite to get a taste of the ways in which the story’s choices are given weight and consequences by a supporting cast of game mechanics.
None of these stakes would be worth a damn if The Banner Saga didn’t feature characters worth saving. It’s all a complex way of determining one thing: who lives. Overspending Renown on Items might mean running out of Supplies, which lowers Morale, in turn weakening your Heroes in battle, leading them to get Injured, which means wasting Time recovering, which may result in the bad guys catching up and characters dying. If you didn’t care about the characters and their goals in the first place, it wouldn’t matter. But my takeaway is this: if writing a lengthy interactive fiction, consider adding a small web of different narrative ‘currencies’ and gameplay resources, and at least some basic relationships between them. Then, once good characters are introduced, your handful of interlocking mechanics will mean that, by liberally sprinkling resource or currency consequences onto outcomes, every choice can be a subtle, nuanced, and engaging dilemma.
The diagram above is the sum of my investigation, and is worth reading to appreciate the complexity this game pulls off. Down the left side, we have various gameplay features, such as Heroes, Battles, Supplies, and Time. Each feature is followed by a description of what it is and/or how it relates to other features. On the right, we have a node representing the game’s narrative choices. But the really interesting part is what happens between the features and the story, so I’ve mapped all the relationships out and labelled them with what can happen. Each feature has two arrows describing its relationship with the story: one going from left to right, showing how the feature can affect the story and what choice options are available; and one going from right to left, showing how narrative decisions made by the player can affect that feature.